Read it and then read it again!

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Read it and then read it again!

AUDIOFROG TUNING GUIDE

Fixed

 

The only thing I would add to that is this:

Jazzy's Tuning Spreadsheet This is VERY useful.

 

Use jazzy spreadsheet to make target [emoji457] curves for EACH driver.


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That's a great resource - thanks. The guides here (Erin's stuff & Hanatsu's) are amazing but are mostly "how to do X" and "why to do X", but not really a step-by-step.

Given that Audiofrog guide, once I get to EQing, I'd be applying any equalization on the input side in the MiniDSP software, right? Not the individual channels.

 

EQing individual channels allows one to closely match the response to each driver’s target

Read all of those references


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That much I get, but that AudioFrog document only shows equalizing full range. Is this a better understanding:

1) EQ each individual driver relative to expected response including crossover (on output side in DSP)
2) EQ L/R relative to house curve and clean up (on input side in DSP)

I'm also working with only 6PEQ on each output and 6 on each input

 

Just wanted to second the questions the op has, especially the question about hitting a target curve.

 

Set gains.
Set TA.
Pull up target curve
Start with tweeters. Mutes everything else
So left or right individually.then other .
Then repeat for all other speakers.
You are equalizing each channel to match the target response curve.

Once all channels are done. Play together and see how closely the overall response matches target curve.

Listen to music you are familiar with and make small adjustments by ear. It should only be .5-1db if the eq process was done correctly and perhaps adjusting levels by a DB or so to adjust the stages.

 

I'm dense....

Set gains, yup - I get that. Set TA, yup - I get that.

So is my target response curve for each individual speaker the house curve I choose, in the frequency portion that applies to that individual speaker? In other words, for the 8" speakers, do I:
1) load in AudioFrog house curve
2) apply 250Hz crossover
3) sweep 20-500Hz
4) Adjust EQ to match that region?

I think the part that is screwing me up is a house curve is full range, whereas I'm only EQing a small portion of that range with individual speaker EQ.

 

Now THAT makes sense. Thanks so much!

 

Glad it's making sense. Make sure to follow Mic10is's recommendation of minimal boosting, too much eq can cause lots of other problems.

 

Jazzi’s spreadsheet is so helpful in individual driver tuning. I’m learning this tuning stuff as well, I still have plenty to figure out, but I first used the Audiofrog approach tuning only the full left and right and then matching one to the other. That worked out ok, there were many tweaks needed to match one side to the other which require live tuning and lots of re-measuring.

I’m now working with the component-level first approach and I think it is a bit easier as I’ll explain.

I first take a measurement of each speaker in REW. Then, I go back inside a use the EQ tool in REW to automatically figure out the filters for that speaker, and I can tweak a little based on the prediction curve. I set the reference curve level so The roll-offs on the crossover sides match the reference best and that the majority of adjustments will be cuts. I note the curve level and repeat for all speakers, noting all of the levels that I used for the reference curves. In REW, you can export a text file with all of the filter settings (one channel at a time). Then either type them in to your DSP or import if that’s supported. On Helix DSP’s, you can work on files offline and import lists of filters by pressing “r” on your keyboard when looking at the desired channel.

Then, I adjust the levels for each speaker channel based on the levels I noted to make them even. Again, make the lowest level speaker the one that stays at 0dB and cut the other channels so that they will all be the same. Say I had 3 speakers, in my notes one was 50dB, another 53, and another 46. I would lower the 50dB channel level by 4 and the 53dB level by 7.

The previous step is a big time saver in my experience. After you’ve input all the filters and changed the levels, get a measurement of the full left + sub and full right + sub. They will likely be very close already and only need a few tweaks to match them. The levels will be basically right on across the spectrum. There’s a good chance you’ll need to figure out some phasing issues between the sub and mid-bass, possibly others as well. Look for big dips at or very near your crossover points as these are probably a phase issue. Flipping polarity of one speaker might help but work carefully here as you’ll then probably need to flip others and this can get confusing quickly.

Once you’ve got the individual sides done, get a measurement with all speakers on. Look at this curve and how it compares to the left and right. The ideal result is that this curve is 3dB higher than the left and right (which would be on top of each other) across the whole range as that is a perfect sum. You will probably see places where it dips below the individual sides, these places are cancellations. Some of them can be addressed depending on the DSP’s capabilities, others may not respond to anything you can do with tuning.

 

Thanks everyone for the feedback. Now, stupid question time:

I'm attempting to set my gains using a DMM. Amp is a Soundstream PN4.1000D. 140WRMSx4 at 4 ohms. No data available for 8 ohms, so I was going to swag it at 100WRMS. Doing the math that I've seen everywhere, (100W x 8 ohms)^0.5 = 28.3VAC.

I set up a test signal in REW using 60Hz -12dB, disabled all the crossovers and muted the channels I wasn't focusing on adjusting gain-wise. Using that test tone, I basically capped out at about 13VAC with max gain.

Is something in my math wrong? Should I adjust that signal in REW?

Edit for posterity: Yes, I did do something wrong. Should use the 0dB signal.

 

A real quick rule of thumb regarding power of an amplifier, most amps are rated into a 4 ohm load. If you halve the load to 2 ohms, the power generally doubles and if you double the load to 8 ohms, the power halves. So, if your amp does 140 watts at 4 ohms, it would do 280 watts at 2 ohms and 70 watts at 8 ohms. This is again a rough estimate because the load of a speaker fluctuates with a change in frequency... not by a huge amount, but enough that some manufacturers warn you about running numerically lower loads.

Regarding setting of amplifier gains, you can use a DMM but as you saw, it can sometimes not yield the expected results when using simple math. The quick and dirty method is to set gains by ear using the 75% head unit volume method;

1. Disconnect the speaker wires from your amp(s)
2. Turn the amp gain controls completely counter-clockwise
3. Set any equalization or tone control to mid-range or 0db
4. Find the max volume point of your head unit;
5. If the unit has a numerical display that goes to, say, 100, multiply the max number by .75 which will give you 3/4 or 75% of its max output.
6. If you just have a knob with no volume display, turn the knob all the way to the right, note the rough position of the knob indicator and then back it off 1/4 of its max range.
7. With the volume set at 75% and the gains all the way down, reconnect one speaker channel.
8. Play some music you are familiar with, something that is not too busy.
9. Turn the gain of the connected channel up until you start to hear buzzing or distortion, then back off just a bit.
10. Disconnect that channels speaker wires again and reconnect the next channels wires.
11. Repeat steps 8 & 9 for this channel
12. Repeat again for remaining channels

This method allows you to essentially crank the volume on your head unit up without overdriving it or the amplifier.

 

Set gains per target curve.
If you are dead set on using DMM, only for sub.
Besides, after you EQ-you may want to turn up the gain in dsp or amp. It’s not sooooo exact!


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Thanks - that's about what I did. HU at 30/40 and adjusted to like 24VAC. After listening, I actually turned it down to I-don't-know levels, but it's plenty loud enough and clear enough at 25/40 on the head unit so I'm happy.

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That said, I had my first go at tuning this evening. I loaded up the individual driver curves as "room" curves in REW, sampled each 5x adjusting mic position a little each time, and used REW's AutoEQ feature set up for my MiniDSP 6x8. Below is a full range L/R measurement. Yes, the 20-40Hz is hopeless - I only have 8" Peerless in the doors and I'm willing to make that sacrifice (this is a Miata, after all), but what I'd really like to fix is that 200-400Hz dropoff. I'm currently using a 350Hz 4th order LR on both the Whispers & Peerless.

My next step is to re-run the individual measurements again, see if that drop is there, and see about boosting that region. It's near the crossover area so it gets a little "fuzzy", doesn't it?

Oh, one other note - that room EQ is incorrect to what I targeted individually. Instead of the +10 shelf from 20-60Hz, I think I had set it to +3 (again, thinking of the Peerless limitations)

 

Neat!
How were the individual curves? Have a look at them to see if you’re dips may be phase related.


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